Draw Reduction Ratio
The proportional reduction in diameter taken in a single draw stage; limited to avoid tearing.
What it means on the floor
The draw (reduction) ratio compares the blank or prior-shell diameter to the drawn diameter. A first draw might safely reduce the diameter by around 40–50%; subsequent redraws take smaller reductions because the material has work-hardened.
Exceeding the limiting draw ratio tears the cup wall. Calculating the number of stages up front prevents splits and wasted tooling.
Category: Forming
Applying the term
Interpret Draw Reduction Ratio in the context of the drawing, governing standard, and customer requirement in front of you — the same word can carry different limits in design, quality, and production documents. Check whether a stated value is nominal, minimum, maximum, or reference-only, and whether it applies before forming, after forming, or after heat treatment.